1. Field of Invention
The current invention relates to electronic and/or electro-optic devices, and more particularly to electronic and/or electro-optic devices that include high dielectric-constant, ionically-polarizable materials.
2. Discussion of Related Art
There are numerous approaches to high-capacitance devices including high-dielectric constant (high-∈) insulators, ultrathin dielectric films, and/or high surface area electrodes. In silicon electronics, SiO2 gate dielectrics that capacitively couple gate voltages to the formation of semiconductor charge carrier channels were shrunk to just a few monolayers before reaching a fundamental breakdown limit; as a result, higher-∈ HfO2 was introduced as a replacement. (S. Duenas, H. Castan, H. Garcia, A. Gomez, L. Bailon, M. Toledano-Luque, I. Martil, and G. Gonzalez-Diaz, Electrical properties of high-pressure reactive sputtered thin hafnium oxide high-k gate dielectrics, Semiconductor Science and Technology 22, 1344 (2007); G. He, L. Q. Zhu, M. Liu, Q. Fang, and L. D. Zhang, Optical and electrical properties of plasma-oxidation derived HfO2 gate dielectric films, Applied Surface Science 253, 3413 (2007); H. Wong and H. Iwai, On the scaling issues and high-kappa replacement of ultrathin gate dielectrics for nanoscale MOS transistors, Microelectronic Engineering 83, 1867 (2006); D. Q. Wu, H. S. Zhao, J. C. Yao, D. Y. Zhang, and A. M. Chang, Development of high-k gate dielectric materials, Journal of Inorganic Materials 23, 865 (2008).) For energy storage, double-layer capacitors utilize the self-limiting thickness of polarized ionic assemblies in solution along with high surface area electrodes made from metallic solids and/or high surface area carbons. (B. B. Garcia, A. M. Feaver, Q. F. Zhang, R. D. Champion, G. Z. Cao, T. T. Fister, K. P. Nagle, and G. T. Seidler, Effect of pore morphology on the electrochemical properties of electric double layer carbon cryogel supercapacitors, Journal of Applied Physics 104 (2008); C. W. Huang, C. M. Chuang, J. M. Ting, and H. S. Teng, Significantly enhanced charge conduction in electric double layer capacitors using carbon nanotube-grafted activated carbon electrodes, Journal of Power Sources 183, 406 (2008); K. Juodkazis, J. Juodkazyte, V. Sukiene, A. Griguceviciene, and A. Selskis, On the charge storage mechanism at RuO2/0.5 M H2SO4 interface, Journal of Solid State Electrochemistry 12, 1399 (2008); D. Pech, D. Guay, T. Brousse, and D. Belanger, Concept for charge storage in electrochemical capacitors with functionalized carbon electrodes, Electrochemical and Solid State Letters 11, A202 (2008); M. M. Shaijumon, F. S. Ou, L. J. Ci, and P. M. Ajayan, Synthesis of hybrid nanowire arrays and their application as high power supercapacitor electrodes, Chemical Communications, 2373 (2008); C. Z. Yuan, H. Dou, B. Gao, L. H. Su, and X. G. Zhang, High-voltage aqueous symmetric electrochemical capacitor based on Ru0.7Sn0.3O2 center dot nH(2)O electrodes in 1 M KOH, Journal of Solid State Electrochemistry 12, 1645 (2008).) The combination of double layer formation and redox processes at the electrode surfaces, which can involve the metallic species or conductive polymer adlayers, leads to a synergistic effect known as supercapacitance. (P. K. Nayak and N. Munichandraiah, Cobalt hydroxide as a capacitor material: Tuning its potential window, Journal of the Electrochemical Society 155, A855 (2008); J. Oh, M. E. Kozlov, B. G. Kim, H. K. Kim, R. H. Baughman, and Y. H. Hwang, Preparation and electrochemical characterization of porous SWNT-PPy nanocomposite sheets for supercapacitor applications, Synthetic Metals 158, 638 (2008); R. K. Sharma, A. C. Rastogi, and S. B. Desu, Manganese oxide embedded polypyrrole nanocomposites for electrochemical supercapacitor, Electrochimica Acta 53, 7690 (2008); J. F. Zang, S. J. Bao, C. M. Li, H. J. Bian, X. Q. Cui, Q. L. Bao, C. Q. Sun, J. Guo, and K. R. Lian, Well-aligned cone-shaped nanostructure of polypyrrole/RuO2 and its electrochemical supercapacitor, Journal of Physical Chemistry C 112, 14843 (2008); H. B. Zhang, H. L. Li, F. B. Zhang, J. X. Wang, Z. Wang, and S. C. Wang, Polyaniline nanofibers prepared by a facile electrochemical approach and their supercapacitor performance, Journal of Materials Research 23, 2326 (2008).) In another alternative, flexible capacitive sheets with highly nonpolar or ferroelectric polymeric dielectrics (Q. Chen, B. J. Chu, X. Zhou, and Q. M. Zhang, Effect of metal-polymer interface on the breakdown electric field of poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) terpolymer, Applied Physics Letters 91 (2007); Q. Chen, Y. Wang, X. Zhou, Q. M. Zhang, and S. H. Zhang, High field tunneling as a limiting factor of maximum energy density in dielectric energy storage capacitors, Applied Physics Letters 92 (2008); B. J. Chu, X. Zhou, K. L. Ren, B. Neese, M. R. Lin, Q. Wang, F. Bauer, and Q. M. Zhang, A dielectric polymer with high electric energy density and fast discharge speed, Science 313, 334 (2006); J. Claude, Y. Y. Lu, K. Li, and Q. Wang, Electrical storage in poly(vinylidene fluoride) based ferroelectric polymers: Correlating polymer structure to electrical breakdown strength, Chemistry of Materials 20, 2078 (2008); M. Rabuffi and G. Picci, Status quo and future prospects for metallized polypropylene energy storage capacitors, IEEE Transactions on Plasma Science 30, 1939 (2002); Z. C. Zhang and T. C. M. Chung, The structure-property relationship of poly(vinylidene difluoride)-based polymers with energy storage and loss under applied electric fields, Macromolecules 40, 9391 (2007)) flanked by metal coatings are coiled to increase capacitance per unit volume. Consequently, there remains a need for electronic and/or electro-optic devices that have improved dielectric structures.